Influence of graphite platelets with and without SiC on the densification and fracture toughness of ZrB 2 ceramic sintered by SPS

Few studies have been performed on ZrB 2 -graphite platelet composite made by spark plasma sintering (SPS) technique. In this research, the influence of adding graphite platelets (Gp) with and without SiC on the fracture toughness of ZrB 2 ceramic was studied. The ZrB 2 -10Gp, ZrB 2 -15Gp, ZrB 2 -30SiC-10Gp, and ZrB 2 -30SiC-15Gp specimens were sintered by the SPS method at the temperature of 1850 °C for 8 min. The fracture toughness and work of fracture (WOF) were evaluated using the Single-Edge Notched Beam (SENB) technique. It was found that the fracture toughness and WOF were improved by the alone and combined addition of Gp and SiC to the monolithic ZrB 2 . The maximum fracture toughness of 4.8 ± 0.1 MPa m 1/2 was obtained for the ZrB 2 -15Gp specimen. It seems that adding Gp alone was more effective in enhancing the fracture toughness of ZrB 2 than the combined addition of Gp and SiC. While the addition of Gp and SiC simultaneously modified the densification behavior to reach full-densified samples.